58 GENERAL THERAPEUTICS FOR VETERINARIANS 



1. The cardiac stimulants are camphor, hyoscine (scopolamine), 

 atropine, caffeine, veratrine, alcohol, ether, ammonia, ammonium 

 carbonate and some of the ethereal oils (valerian, arnica). These 

 act in part by paralyzing the vagus, the nerve of inhibition, cen- 

 trically or peripherally; in part by stimulating the sjnnpathetic 

 nerve and the vasomotor centre, and in part by stimulation of the 

 heart muscle. 



2. The cardiac tonics are digitalis, strophanthus, squill, spar- 

 teine, adonidin and convallamarin. These stimulate the vagus 

 centrically and peripherally, and also the heart muscle. 



3. The cardiac sedatives are potassium bromide, chloral hy- 

 drate and potassium iodide. These act in part by depressing the 

 cardiac centre in the medulla oblongata and in part by depressing 

 the cardiac muscle. 



Uses. — 1. The cardiac stimulants are prescribed in all cases of 

 acute heart weakness such as may occur in the course of acute 

 heart diseases, febrile infectious diseases and poisoning; also in 

 syncope. The most important symptoms of heart weakness are a 

 weak or imperceptible, very frequent or slow pulse; in the begin- 

 ning a throbbing heart beat, which is later weak or imperceptible; 

 indistinct heart sounds, dyspnoea, cyanosis of the mucous mem- 

 branes, collapse. 



2. The cardiac tonics are specific for chronic heart diseases, 

 particularly valvular defects in the stage of insufficiency. They 

 increase the force of contraction of the heart muscle, slow and 

 regulate the rate of contraction, increase the length of the pause 

 between beats, and increase the blood-pressure. They are indi- 

 cated when the pulse is abnormally rapid, irregular and weak, and 

 the heart is beating tumultuously. On the other hand, they are 

 contraindicated in valvular insufficiency when compensatory 

 hypertrophy has occurred, in cardiac hypertrophy, in palpitation 

 and in all cases in which the pulse is strong or the heart beat abnor- 

 mally slow (bradycardia). 



3. The cardiac sedatives are prescribed in cardiac excitement 

 of nervous origin, particularly palpitation. 



Drugs. — 1. Digitalis. The most important cardiac for val- 



